Two families are suing the NYPD for $21 million, saying narcotics cops, acting on bad information stormed their homes in a pair of terrifying “no-knock” raids.

A raid on the home of two retired law-enforcement officers nearly turned deadly, says a $9 million federal suit filed yesterday by Robert and Marie Rogers.

Robert had his gun aimed and ready to shoot when cops busted through the door of his Queens home on Oct. 15, 2002.

The 64-year-old former housing cop said he reacted quickly – tossing his weapon and himself to the ground to show he wasn’t a threat.

“We both thought we were going to die that night,” said Marie, a 63-year-old retired correction officer.

Attorney Norman Siegel filed a second, $12 million suit yesterday on behalf of a Brooklyn mother and her twin 13-year-old sons who were handcuffed and grilled about non-existent drugs after a bad bust-in.

About six months after these searches, tragedy sparked public outcry over the NYPD’s search policies when Alberta Spruill, a 57-year-old Harlem woman, suffered a fatal heart attack during a raid sparked by a bad tip.

A police spokesman said yesterday that policy changes, such as having high-level officials review search warrants, make mistakes less likely.

According to the second suit, Willie Mae Mack, 40, and her sons, Darnell and Edward Myers, were menaced by cops after being jolted out of bed by the sound of an exploding flash grenade in the early-morning hours of Sept. 3, 2002.